Overshots are available in the oilfield service industry. Overshots are described in the composite catalog at Pages 654 et seq. Some of the overshots shown are able to grasp a fish and lift it. However, they typically are limited in release operations. One common releasing and circulating overshot is released only by jarring down heavily and rotating simultaneously to the right. This limits the running of such a tool to a tubing string. It is inconvenient to assemble a tubing string and particularly snub it into a high pressure well to provide service to a down-hole tool. This is merely representative of overshots known in the past which are limited in that they can be run readily on a tubing string or wireline to engage a fish. However, they generally cannot be easily released without partly destroying the tool or requiring a tubing string for rotation to the right. Tools of the prior art are believed deficient in providing an overshot which can be run on a wireline and be releasable without destroying the tool.
Some overshots are released by heavy jarring which shears a pin or the like. Such jarring is so forceful that it is likely to damage down-hole equipment. Survey instruments sometimes must be fished from the hole, and an overshot can be used to grasp the instrument for retrieval. If it is hung and a heavier overshot must be used, heavy jarring is required to free the overshot from the survey instrument. Survey instruments are formed of small, delicate instrumentation and can easily be damaged by jarring. It is inconvenient and difficult to use rotation to release overshots because they require a tubing string to transmit torque, while a wireline is much cheaper to run.
The present invention is a releasable wireline overshot which releases on an up and down reciprocating motion and not on rotation or heavy jarring. This enables it to be run on a wireline which is far more convenient than a tubing string.